Machine pistol

ABSTRACT

Automatic weapon having a unitary fire control group including a burst control counter rotatable in one angular direction from a starting position in synchronism with hammer release and which is automatically self resetting in the opposite angular direction upon trigger release, the fire control group being releasably connected to a frame and barrel group for snap locking assembly with a receiver, the frame and barrel group being releasably secured to the receiver by a takedown latch rotatably supported on a muzzle end of the receiver, and a gas operated piston supported for reciprocation on the barrel and having a forwardly projecting skirt circumferentially surrounding a muzzle compensator and jointly defining therewith a gas chamber when the piston is in a forward operative limit position and providing forwardly directed gas blowout.

[ MACHINE PISTOL [75] Inventor: Henry A. Into, Farmington, Conn.

[73] Assignee: Colt Industries Operating Corp., Hartford, Conn.

[22] Filed: Oct. 12, 1971 [21] Appl. No.: 188,081

[52] U.S. Cl. 89/129 A, 89/142 [51] Int. Cl. F4ld 11/02, F4ld 11/08 [58] Field of Search 89/129, 140, 142

[56] References Cited UNITED STATES PATENTS 12/1958 Kunz 89/129 12/ 1966 Sturtevant 89/ l 29 Primary Examiner-Stephen C. Bentley Attorney-John M. Prutzman et al.

[ 51 Nov. 27, 1973 [57] ABSTRACT Automatic weapon having a unitary fire control group including a burst control counter rotatable in one angular direction from a starting position in synchronism with hammer release and which is automatically self resetting in the opposite angular direction upon trigger release, the fire control group being releasably connected to a frame and barrel group for snap locking assembly with a receiver, the frame and barrel group being releasably secured to the receiver by a takedown latch rotatably supported on a muzzle end of the receiver, and a gas operated piston supported for reciprocation on the barrel and having a forwardly projecting skirt circumferentially surrounding a muzzle compensator and jointly defining therewith a gas chamber when the piston is in a forward operative limit position and providing forwardly directed gas blowout.

20 Claims, 13 Drawing Figures PATENIEUNDYZY I975 SHEET l U? PATENTED NOV 27 I975 SHEET 3 SF 6 PATENTEU am 2 7 I975 ETQUF 6 WHENIEHNUYE'I I975 I SHEET SD? 6 PATENIED unv 2 7 I975 sum 6 c; s

MACHINE PISTOL This invention generally relates to firearms and particularly concerns automatic machine pistols.

A primary object of this invention is to provide an automatic, gas operated, hammer actuated machine pistol incorporating a minimum number of operating parts in a lightweight compact weapon package which is quick and easy to manufacture and is particularly suited for facile field stripping and reassembly.

Another object of this invention is to provide a machine pistol of the above described type having a significantly improved arrangement of fire control components selectively providing single shot and controlled burst modes of fire.

A further object of this invention is to provide an improved machine pistol having a simplified bolt assembly featuring a bolt locking block for automatically and positively retracting the firing pin in timed relation to bolt recoil and additionally serving to actuate hammer release upon bolt locking during counter-recoiler in a burst mode of fire.

Other objects will be in part obvious and in part pointed outin more detail hereinafter.

A better understanding of the objects, advantages, features, properties and relationships of the invention will be obtained from the following detailed description and accompanying drawings which set forth an illustrative embodiment and is-indicative of the way in which the principle of the invention is employed.

In the drawings:

FIG. 1 is a side view, partly broken away and partly in section, showing a machine pistol incorporating this invention;

FIG. 2 is a side view, partly broken away, showing a bolt operating mechanism and fire control group of the pistol of FIG. 1;

FIG. 3 is an enlarged end view showing a take-down latch on a muzzle end of the pistol;

FIG. 4 is a longitudinal section view, partly broken away, of a bolt assembly of the pistol in a locked position;

FIG. 5 is a view similar to FIG. 4, showing the bolt as sembly in unlocked position; 1

FIG. 6 is an enlarged cross section view taken generally along lines 6-6 of FIG. 5;

FIG. 7 is a side view, partly broken away and partly in section, of a fire control group incorporated in the pistol of this invention;

FIG. 8 is a bottom plan view, partly broken away and partly in section, of the fire control group of FIG. 7;

FIG. 9 is a schematic view, partly broken away and partly in section, showing a combination safety and firing mode selector and counter catch of the fire control group;

FIG. 10 is a schematic view, partly broken away and partly in section, showing a sear and burst sear trip of the fire control group incorporated in the pistol of this invention; and

FIG. 11 is a schematic view, partly broken away and partly in section, similar to FIG. 9 wherein the combination safety and firing mode selector and counter catch of fire control group are shown in conjunction with the hammer and sear in safety ON position;

FIG. 12 is a schematic view, partly broken away and partly in section, similar to FIG. 11 but with the firing mode selector in a single shot mode of fire; and

FIG. 13 is a view similar to FIG. 11, partly broken away and partly in section, with the firing mode selector in a burst fire control position.

Referring in detail to drawings, a machine pistol 10 is shown incorporating a preferred embodiment of this invention wherein a unitary fire control group 12 is 7 supported on a rear portion of a receiver 14 and is operatively connected to a frame and barrel group 16 extending longitudinally of an elongated barrel portion 18 of the receiver, 14 which is provided with a removable cover 20. The illustrated machine pistol 10 is an automatic weapon having a gas operating system including a piston 22 which is spring biased toward a forward limit position and supported for reciprocation on a barrel 24 extending forwardly of a frame 26. The piston 22 is fixed to an operating rod 28, which not only serves to reciprocate a bolt assembly 30, mounted in the frame 26, but also conditions the fire control group 12 for firing a chambered round, not shown, from a closed bolt upon hammer actuation.

Illustrations and detailed description of conventional features such as the barrel chamber, extractor, ejector, magazine and cartridge stripping and chambering functions have been omitted since they are not essential to an understanding of this invention. 7

To effect quick and easy field stripping and reassembly of the machine pistol component groups, a simplified snap locking system is provided for releasably assembling the component groups in operative relation within the receiver 14 and a takedown muzzle latch 32 is rotatably mounted on a muzzle end of the receiver 14 for securing and releasing the component groups.

More specifically, a reinforcing bolt slide support and stop member 34 is fitted'within a rear portion of the receiver 14 and has a pair of upstanding resilient lugs (only one shown at 36) extending upwardly from an upright rear wall portion of member 34. The lugs 36 have an arcuate configuration to embrace a takedown pin 38 extending laterally across and supported on opposite sidewalls 40 of a fire control housing 42. A forward wall of the housing 42 has a rearwardly projecting lower tongue 44 engageable within-conforming groove 46 extending laterally across an upper rear end of the frame 26. A rearwardly projecting rib 48 is formed on the bottom of the frame 26 at its rear end for seating engagement under member 34 within a corresponding recess 50 within the receiver 14 behind an upper portion of a magazine well 52 formed in a pistol grip of the receiver 14.

To reinforce the receiver 14 from bolt locking impact and relieve any resulting stress transmitted from the frame 26 to the receiver 14, a cross pin 54 is secured in the receiver 14 in front of an upper portion of its magazine well 52. The cross pin 54 additionally serves to engage a lug 56 depending from the front base of the frame 26.

A breech 58 extends forwardly of the frame 14 with the breech 58 in integral coaxial relation to the barrel 24, and an attachment or compensator 60 is threadably mounted for rotation in coaxially surrounding relation to the muzzle of the barrel 24. The compensator 60 has a pair of external planar'surfaces 62 on diametrically opposed sides of the compensator 60 serving as selflocating flats for the compensator 60 relative to its barrel 24. The takedown latch 32 has a parti-circular locking rim 64 engaging the muzzle end of the receiver barrel portion 18 and defining a generally U" shaped opening 66 which is dimensioned to conform to the exterior configuration of the compensator 60 and a relatively restricted exposed top opening 68 in the muzzle end of the receiver barrel portion 18. A radial projection 70 is formed on the locking rim 64 adjacentits open side, and a latch lever 72 is supported on the projection 70 for swinging movement about a pivot pin 74 perpendicular to the receiver barrel portion 18 with an opening 76 in the lever 72 to permit its being fitted over a front sight 78 on the receiver cover 20.

To assemble the component groups within the receiver 14, the front tongue 44 of the fire housing 42 is first engaged within the rear locking groove 46 in the frame 26, and the fire control housing 42 is then seated on the upper rear portion of the receiver 14 with its resilient lugs 36 engaging the takedown pin 38 in position to urge the fire control housing toward the rear of the receiver 14. The takedown latch 32 is rotated to orient its U" shaped opening 66 relative to the receiver 14 such that its muzzle end willfreely receive the compensator 60 with its self-locating flats 62 positioned parallel to the sides of the opening-66. A charging handle 80 formed on the operating rod 28 may then be retracted rearwardly against the bias of its action spring 82 (shown coiled about the barrel 24 withtopposite-ends of the spring 82 seated against shoulders-84 and 86 on the breech end of the barrel 24 and the gas piston 22) to withdraw the piston 22 a sufficient distance to clear the restricted top opening 68 in the muzzle end of the receiver barrel portion 18 permitting the compensator 60 to be seated into the U" shaped opening 66 of the latch locking rim 64 whereupon the front lug 56 ofthe' frame 26 is simultaneously snap locked into engagement with the cross pin 54' with the rear rib 48 of the frame 26 confined in the recess 50 of the receiver 14. The frame 26 is accordingly secured in operative position on the receiver 14, and the takedown pin 38 of the fire control housing 42 is suitably disposed in the housing to exert a forwardly directed force against the resilient locking lugs 36 of the frame 26 when the housing 42 is secured in engagement with the receiver 14. The cover 20 may then be mounted onto the receiver 14. For this purpose, a recess 88 is formed in a rear wall of the cover 20 for receipt of a forwardly projecting shoulder 90 on an upper front portion of the frame 26 upon pivoting the cover 20 downwardly into engagement .with the receiver barrel portion 18, thereby to fit an arcuate terminal projection 92 on the forward end of the cover 20 into the restricted top opening 68 in the muzzle end of the receiver barrel portion 18 so as to overlie the compensator 60. The latch 32 may then be simply rotated 90 over the projection 92 of the cover 20 to automatically rotate the compensator 60 into a firing position while at the same time positioning the lever 72 to be pivoted rearwardly over the from sight 78 of the cover 20 and into a locked position constrained'against unintended angular displacement between a pair of front sight protective ears 94 shown projecting upwardly from opposite sides of the cover 20. A forward limit position of the operating rod 28 and its integral gas piston 22 is established by seating-engagement of the bolt 30 against the frame 26, the bolt 30 being reciprocably mounted for movement longitudinally of the receiver 14 within the frame 26. -A laterally projecting rear bolt lug 96 extends into a cam' slot 98 formed in the operating rod 28', and, upon bolt clo sure, servesas a stop upon lug 96 engaging a rear wall 100 of the cam slot 98 as the rod 28 is driven forwardly by its action spring 82. A rear limit position of the reciprocating operating rod-28 is provided by engagement of a-front bolt lug 102 with a front wall 104 of cam-slot .98.when the rod 28 drives the bolt rearwardly into engagement with the stop member 34 secured tothe receiver 14.

v To reduce the bulky size and number of parts frequently associated with automatic gas operated weapons of this general type, the pistion 22 is formed with av forwardly. projecting warp-around skirt 106 which circumferentially surrounds a rear portion of the compensator 60 when the pistion 22 is in its forward limit position. The disclosed concentric arrangement of the barrel 24, compensator 60 and piston 22 defines a confined annular clearance when the operating rod 28 and piston 22 are in their forward limit position, providing a gas chamber 108 for the machine piston 10. The gas chamber 108 communicates with a bore 110 of the barrel 24 through suitable ports such as at 1 l2 whereupon combustion by-products formed upon the firing and exiting of a projectile from the barrel 24 will drive the gas pistion 22 and operating rod 28 rearwardly against the bias of the action spring 82 to effect extraction and ejection of a spent cartridge case from the chamber, and the recoiling mass automatically sears up a hammer 114 of the fire control group 12 as fully described below.

The simplified concentric relationship of the barrel, compensator and piston not only is readily and economically manufactured and assembled but also facilitates quick and easy disassembly and reassembly. In addition, the disclosed wrap-around piston skirt 106 minimizes powder fouling under extended service usage while also reducing gas impact loads on the receiver 14 due to the resulting forwardly directed gas blowout.

To insure bolt opening and closure in properly timed relation to the operation of the fire control group 12, the front bolt lug 102 received in the cam slot 98 of the operating rod 28 engages the front wall 104 of the slot 98 after initial rearward movement of the operating rod 28 from its forward limit position. To positively'retract a firing pin 116 upon bolt opening to condition the firing pin 116 for firing the next chambered round upon squeezing a trigger 118 supported on a pivot pin 120 mounted on the base of the frame 26, a tilting bolt locking block 122 is mounted on the bolt 30 for pivotal movement about an axis transverse to the path of bolt movement. A pair of spaced opposed camming ears 124, 124 project downwardly from the locking block 122 for receipt within the confines of the bolt 30 and within corresponding grooves 126, 126 formed on opposite sides of the firing pin 116 for continuously maintaining the firing pin 116 in operative assembly with the bolt 30 while also positively retracting the firing pin 116 within its firing pin passage 128 during hammer cocking upon bolt retraction.

During recoil, rearward movement of the operating rod 28 drives an elongated bolt catch 130 rearwardly,

:and a downwardly turned finger 132 of the bolt catch bolt catch 130 pivots downwardly, a lower contoured surface 140 of the cam slot 98 engages the locking block cam 138 to pivot the tail of the locking block 122 downwardly, to disengage its rear wall 141 from rear wall 142 of the frame 26, and positively retracts the firing pin 116 against the hammer 114 and locks the pin 116 in its retracted position.

More specifically, FIIGS. 1 and 7 show the bolt 30 locked against wall 142 by the rear wall 141 of the locking block 122. FIG. 4 illustrates the hammer 114 in firing position wherein it will be seen that the tail of the locking block 122 is in a tilted position relative to its position shown in FIG. 5 wherein the bolt 30 is unlocked with its locking block 122 in lowered disengaged relation to the frame 26 in condition to return the hammer 114 to re-engage its sear 144 (FIG. 7) as fully described below. In FIG. 5, the ears 124, 124 of the locking block 122 have been driven downwardly into the grooves 126, 126 in the firing pin 116, and it will be noted that the ears 124, 124 positively engage rear shoulders, such as at 145, to effect positive firing pin retraction to the broken line position at 146 in FIG. 4 during the downward pivoting movement of the locking block 122 from its locking position in FIG. 4 to its disengaged position in FIG. 5.

Continued rearward movement of the operating rod 28 causes its front slot wall 104 to engage the front bolt lug 102 to open the breech as the piston 22 is driven rearwardly, whereupon the bolt 30 drives the hammer 114 about a pivot pin 148, mounted crosswise in the fire control housing 42, to re-engage the hammer 114 with sear 144 for the firing of the next round. During bolt reciprocation, the bolt catch 130 not only restricts undesired relative motion between the operating rod 28 and bolt 30 but additionally restricts undesired movement of the locking block cam 138 to ensure that the locking block 122 is continuously maintained in locking engagement with the firing pin 116 whereby substantially simultaneous movement of the operating rod, bolt, locking block and firing pin is achieved during reciprocation of the bolt 30.

On counter recoil, the driving force of the compressed action spring 82 simultaneously moves both the operating rod 28 and the bolt 30, via the driving connection between the bolt catch 130 and front bolt lug 102, toward the forward limit position. During a terminal portion of the counter recoil cycle, the bolt 30 reengages the frame 26 and the bolt catch 130 overrides the front bolt lug 102 to pivot upwardly into recess 150 underlying the camming surface 134 within the frame 26 as the locking block cam 138 engages an upper contoured surface 152 of the operating rod cam slot 98 to pivot the tail of the locking block 122 upwardly into locking engagement with the frame 26 while the operating rod 28 continues to move relative to the bolt 30 into the forward limit position. The firing pin 116 is then once again unlocked relative to the locking block 122 and remains retracted under the influence of its return spring 154 to be thrust forwardly under hammer impact to fire a chambered round.

In the preferred embodiment, an arcuate shoulder 156 is integrally formed on the front end of the locking block 122 for captured pivotal movement within a conforming opening 158 of the bolt 30. The number of required parts of the locking block and bolt construction of this invention is accordingly minimized and no necessity even exists for spring biased plungers, retaining pins, pivot pins and the like. The described construction additionally facilitates quick and easy field stripping while eliminating any requirement for tools to disassemble and reassemble the components of the bolt assembly.

The previously described trigger squeeze causes forward movement of a trigger bar 160 (FIG. 1) interconnecting trigger 118 with an actuating lug 162 of a sear lever 164 of the fire control group 12. The sear lever 164 is mounted adjacent the sear 144 which is pivotally supported, together with the sear lever 164, on a common cross pin 166 mounted in the sidewalls 40, 40 of the fire control housing 42. As viewed in FIG. 8, the

' sear 144 and sear lever 164 are each provided spring seats 168, 170 adjacent the cover of the fire control housing 42 and are both continuously urged in a clockwise direction as viewed in FIG. 7 respectively by springs 172 and 174 engaging a spring seat bar 176 fixed to a cover of the fire control housing 42. To limit sear lever movement in a clockwise direction as seen in FIg. 7, the spring seat bar 176 has a downwardly projecting finger 178 serving as a stop against which the sear lever 164 is normally engaged. The sear lever 164 has an opening 180 providing a seat for a spring 182 which engages a counter catch 184 also supported for swinging movement about the cross pin 166 independently of the sear 144 and sear lever 164, and the spring 182 continuously urges the counter catch 184 in a counterclockwise direction as seen in FIG. 7 away from the lug 162 of scar lever 164 and toward engagement with an offset stop surface 186 on the sear lever 164. Accordingly, the sear lever 164 is normally positioned against stop finger 178 in spaced apart relation to the counter catch 184 due to the resilient connection effected by the spring 182.

A combination safety and firing mode selector 188 is mounted on the sidewall 40 of the fire control housing 42 and is provided an external finger piece 190 movable between selected detented positions, for example, a safety ON position .(FIG. 11), a single shot fire control position (FIG. 12) and a burst fire control position (FIG. 13). Drivingly connected to the finger piece 190 is a control cam 192 disposed for rotation adjacent the sidewall 40 inside the fire control housing 42. The control cam 192 is provided with suitable camming surfaces such that when the finger piece 190 is in safety ON position (FIG. 1 1), the surface 194 blocks counterclockwise movement of the counter catch 184 as seen in FIGS. 7 and 9 which in turn limits counterclockwise movement of the sear lever 164 which engages the counter catch 184 blocked against movement by the selector 188. Such movement of the sear lever 164 is insufficient to permit is offset abutment 196 to engage a lower abutment surface 198 of the sear 144 and move it upwardly out of engagement with a sear shoulder 200 fonned on the hammer 114.

Accordingly, the hammer 114 is continuously retained in cocked position by engagement with the sear 144 in condition to be fired upon actuation of the sear 144 and to be thrust forwardly under the bias of its hammer spring 202. Opposite ends of the hammer spring 202 engage a spring seat 204, rotatably supported by the housing sidewalls 40, and an enlarged diameter portion of a hammer strut 206. The opposite end of the strut 206 is received for movement within the rotary spring seat 204, and a bifurcated end or fork 207 adjacent the enlarged diameter portion of strut 206 provides a flat segment 208 engageable with an intermediate flat segment 210 on a pin 212 of a counter drive crank 214 (FIG. The crank pin 212 is rotatably supported on two spaced opposed ears 216 on a rear face of the hammer 1 14 (FIG. 8). Upon rearward bolt movement, the hammer 114 is pivoted away from the firing pin 116 in a clockwise direction as seen in FIG. 7 and hammer sear shoulder 200 overrides a complimentary engagement shoulder 218 of the sear 144 whereupon the sear 144 releasably maintains the ham mer 114 in cocked position upon return bolt movement to battery position. With the hammer 1 l4 urged in a counterclockwise direction by its spring 202 as seen in FIG. 7, the sear spring 172 is further compressed due to a slight rearward displacement of the sear 144 on its cross pin 166 relative to the sear lever 164, to an extent limited by an elongated hole 220 in the sear 144 receiving the cross pin 166 (FIG. 10). By this construction, the lower abutment surface 198 of the sear 144 is positioncd for engagement with the offset abutment 196 of the sear lever 164 for subsequent hammer release.

In the Y single shot mode of fire, the combination safety and firing mode selector 188 is moved counterclockwise into a selected detented position such as the full line position shown in- FIGS. 9 and 12 wherein, upon trigger actuation, the sear lever 164 and counter catch 184 both pivot counterclockwise a distance sufficient for the offset abutment 1960f the sear lever 164 to engage the lower abutment surface 198 of the sear 144 and drive it counterclockwise to ride off the hammer sear shoulder 200. The hammer 114 is accordingly released to be driven forwardly under the thrust of its spring into engagement with the firing pin 116 to fire a chambered round. The surface configuration of the selector control cam 192 limits counter catch movement in the singleshot mode of fire to an angular displacement insufficient to permit the counter catch 184 to engage a rotary burst control counter 222.

To provide a counting function automatically responsive to hammer actuation in the burst mode of fire while additionally providing automatic self-resetting of the burst control counter 222 upon trigger release in a fire control group having a minimum number of compactly arranged parts, the burst control counter 222 is supported for rotation on the same pivot pin 148 as the hammer 114. A return torsion spring 224 is suitably coiled within the hub of the counter 222 about the pivot pin 148 with ends of the spring 224 extending in opposite axial directions and fixed within openings, not shown, in the counter 222 and hammer 114 for urging the counter 222 clockwise as seen in FIG. 7. Simultaneous counterclockwise movement of the counter 222 with the hammer 114 upon its release is effected by the counter drive crank 214 through its offset pawl 226 which is successively engageable with ratchet surfaces 228,. 230 and 232 upon automatic firing of the pistol 10 in the burst mode of fire. With the firing mode selector 188 rotated counterclockwise beyond that position shown in FIG. 9 and into a dentented burst mode of fire shown in FIG. 13, the control cam surface 234 permits sufficient angular displacement of the counter catch 184 under its spring bias to successively engage ratchet surfaces 236, 228 and 230 responsive to continued counterclockwise movement of the counter 222 whereby the torsion spring 224 applies increasing torque loading to the counter 222 is a clockwise direction,

With the hammer 1 l4 seared up in a cocked position, the hammer spring 202 coiled about the hammer strut 207 applies a spring force to the hammer strut fork 207 urging its flat segment 208 into mutually mating surface engagement with the flat segment 210 formed on the pin 212 of the counter drive crank 214. The flat segment 210 of the crank pin 212 is oriented with respect to its axis such that, under the above described seared up hammer condition in mating surface engagement with the flat segment 208 of the hammer strut fork 207, the counter drive crank 214 is disengaged and retracted under hammer spring bias relative to the ratchet surfaces of the burst control counter 222.

Upon hammer release, the pivotal connection between the hammer strut 206 and the hammer 114 remains fixed relative to the hammer pivot pin 148 which serves as an axis of rotation for the hammer 114 and counter 222. Accordingly, hammer strut movement is a combination translatory and angular movement about pivot pin 148. During such movement the counter drive pawl 226 is initially driven by the hammer spring 202 is a controlled fashion along a substantially linear path of movement, effected by the mutually mating engagement of the flat segments 208, 210 of the hammer strut fork 207 and the counter drive pin 212, and into driving engagement with an adjacent ratchet surface of the counter 222. Continued hammer fall about pivot pin 148 toward the firing pin 116 causes the flat segments 208 and 210 to move relative to one another while the hammer spring 202 urges the hammer strut fork 207 into engagement with an upper edge of the flat segment 210 of the crank pin 212. The counter drive crank 214 is accordingly biased clockwise about its pin 212 into driving engagement with the counter ratchet during hammer fall, while yet permitting the offset counter drive pawl 226 to ride in a clockwise direction (FIG. 7) over the ratchet surfaces of the counter 222 and return to a retracted noninterfering position relative to the counter 222 during subsequent hammer cocking in the opposite angular direction upon bolt retraction after cartridge firing during the recoil cycle.

To automatically effect burst firing upon trigger squeeze with the selector 188 conditioned as described above for the burst mode, a sear control or burst seat trip 240 is mounted on the cross pin 166 for simultaneous rotation with the sear 144 while permitting relative longitudinal movement between the sear 144 and the burst sear trip 240. More specifically, the burst sear trip 240 comprises a generally linear, elongated arm 242 supported on the pivot pin 166 with a depending front wall portion 244 disposed in adjacent facing relation to an offset coaxial cam 246 of the counter 222 having protruding lobes 248 and 250 for contact engagement with the front wall portion 244 of the burst sear trip 240. The arm 242 has an intermediate opening 252 of enlarged size relative to the cross pin 166 to permit both rotary and longitudinal movement of the arm 242 relative to the cross pin 166. A rear end portion 252 of the arm is disposed behind pin 166 and turned inwardly to provide a seat for one end of a spring 254 having its opposite end received within a recess 255 in a rear wall of the sear 144 to bias the sear 144 forwardly for engagement with the hammer sear shoulder 200 and to bias the burst sear trip 240 rearwardly. The sear 144 has a laterally projecting stud 256 adjacent its forward swinging end, which is receieved within a longitudinally extending slot 258 in the arm 242 of the burst sear trip 240. The slot 258 is of a greater length than the sear stud 256, permitting relative longitudinal movement of the sear-144 and the arm 242 but capturing the sear stud 256 for simultaneous rotary movement of the sear 144 and burst sear trip 240. The bias of the sear spring 172 normally urges the sear 144 and burst sear trip 240 clockwise as seen in FIGS. 7 and 10, and the hammer pivot pin 148 serves as a stop upon being engaged by the arm 242.

With the firing mode selector 188 in burst mode of fire, trigger actuation effects release of the hammer 114 via operation of the sear lever 164 to trip the sear 144, causing the hammer 114 to drop and simultaneously drive the counter 222 counterclockwise by the counter drive pawl 226 engaging ratchet surface 228.

During this rotary movement of the counter 222 during hammer drop, camming lobe 248 of the counter cam 246 moves into engagement with the front wall portion 244 to position a downwardly extending finger 257 of the burst sear trip 240 into the path of movement of the tail of the tilting locking block 122 upon its being pivoted upwardly after the bolt 30 has come to rest against the frame 26. During the recoil cycle and with the trigger actuated, the sear lever lug 196 remains in a raised actuated position and sear spring 172 dis places the sear 144 forwardly and downwardly relative to the lug 196 which is received in an overlying notch 259 on the bottom of the sear 144 to permit the hammer 114 to be seared up while the counter catch 184 automatically prevents counter reset by engaging the ratchet surface 236 (whereupon the ratchet surface 230 will be engaged next by the counter drive pawl 226 upon firing the next round). With the trigger actuated, the next round is automatically fired as cam lobe 248 maintains the trip finger 257 in the path of the tail of the locking block 122, to effect a uniform lifting movement of the sear 144 with that of the burst sear trip 240, by means of the stud 256 of the sear 144 received within the slot 258 of the burst sear trip 240, while yet permitting longitudinal movement of the sear 144 relative to the trip 240 under the hammer spring bias during hammer sear engagement following firing. Simultaneously with hammer release, drive pawl 226 indexes ratchet surface 230 and the counter catch 184 engages ratchet surface 228 in advanced indexed position as the hammer 114 returns for sear engagement during recoil and is again automatically fired as camming lobe 250 maintains the burst sear trip 240 in position to be tripped by the locking block 122. As the third round is automatically fired and the counter drive pawl 226 drives ratchet surface 232 and the counter catch 184 catches ratchet surface 230, the hammer l 14 returns to be seared up. However, upon firing the third round, the configuration of the counter cam 246 permits the burst sear trip 240 to return under the force of the spring 254 into its illustrated lowered position shown in full lines whereupon the tail of the locking block 122 bypasses trip finger 257 to automatically discontinue burst firmg. Y

Subsequent trigger release causes clockwise movement of the counter catch [84 under the force of the sear lever spring 174 and the counter 222 is automatically self-resetting under its stressed torsion spring 224 to rotate clockwise to an extent limited by engagement of offset counter catch lug 184A by a radially offset stop surface 260 of the counter 222 to once again condition the fire control group 12 for firing the next chambered round. Should the magazine be emptied during the course of a burst, trigger release will again automatically reset the counter 22 as described above, regardless of the number of rounds which have been fired short of a complete burst cycle.

While the counter has been described in the specifically illustrated embodiment as providing a controlled burst of three rounds, the pistol obviously may be adapted to provide bursts of varying maximum numbers of rounds.

A machine pistol incorporating the above described features is not only particularly suited to be quickly and easily manufactured and assembled but is readily field stripped and reassembled without requiring any special tools. The disclosed takedown is not only simplified and effective, but is embodied in a construction having a minimum number of parts, particularly in view of the concentric arrangement of the compensator and gas piston system which further reduces the number of parts and the weight of the assembled weapon components. The multiple functions performed by the bolt are achieved in a compact self-contained assembly designed to provide extended service usage under rugged conditions with limited requirements for field maintenance. The oscillating burst control counter effects automatic self-resetting and performs a true counting function wherein a driving connection is provided between the actuating mechanism and the burst control counter to achieve a preselected count.

As will be apparent to persons skilled in the art, various modifications, adaptations and variations of the foregoing specific disclosure can be made without departing from the teachings of the present invention.

1 claim:

l. A firearm comprising a frame, bolt means mounted on the frame for movement between a locked battery position and an unlocked recoil position, and a fire control mechanism operatively mounted on the frame and including a hammer movable from a firing position to a cocked position responsive to movement of the bolt means from its battery position to recoil position, the hammer being spring biased toward its firing position, a scar engageable with the hammer for releasably maintaining it in cocked position, and a selectively operable burst control means including a bolt operated automatic sear control operatively engaging the sear for hammer release upon movement of the bolt means to locked battery position, a counter movable responsive to hammer movement from cocked position to firing position for providing repeated hammer actuation of a preselected count, and a cam movable in synchronism with movement of the counter for selectively positioning the automatic sear control relative to the path of movement of the bolt means to effect said preselected count, the automatic sear control being disposed by the counter-operated cam in interfering relation to the path of bolt means movement into locked battery position to repeatedly operate the sear to effect ham- 2. The firearm of claim 1 further including a manually actuatable trigger mounted on the frame, connecting means connecting the trigger and the sear, the hammer and the counter being rotatably supported on a common pivot pin mounted on the frame.

3. The firearm of claim 1 further including a disengageable positive driving connection between the hammer and the counter drivingly engaging the counter during hammer movement from cocked position to firing position for indexing the counter during hammer actuation, the positive driving connection between the hammer and the counter being disengaged upon return movement of the hammer from firing position to cocked position.

4. The firearm of claim 1 wherein a manually actuatable trigger is mounted on the frame for operating the sear to release the hammer, wherein the burst control means effects repeated hammer actuation of a preselected maximum count established by the counter cam, and wherein automatic hammer actuation may be interrupted by release of the trigger to effect a countless than said preselected maximum count.

5. The firearm of claim 1 further including a fire mode selector for conditioning the counter to provide the counting function.

6. A firearm comprising a frame, bolt means mounted on the frame for movement between a locked battery position and an unlocked recoil position, and a fire control mechanism operatively mounted on the frame and including a hammer movable from a firing position to a cocked position responsive to movement of the bolt means from its battery position to recoil position, the hammer being spring biased toward its firing position, a sear engageable with the hammer for releasably maintaining it in cocked position, and a selectively operable burst control means including a bolt operated automatic sear control operatively engaging the sear for hammer release upon movement of the bolt means to locked battery position, a counter movable responsive to hammer movement from cocked position to firing position for providing repeated hammer actuation of a preselected count, a cam movable in synchronism with the counter for selectively positioning the automatic sear control relative to the path of movement of the bolt means to its locked battery position to effect 'said preselected count, a disengageable position driving connection between the hammer and the counter drivingly engaging the counter during hammer movement from cocked position to firing position for indexing the counter during hammer actuation, the positive driving connection between the hammer and the counter being disengaged upon return movement of the hammer from firing position to cocked position, the counter having ratchet teeth and a stop surface in offset relation to the ratchet teeth, a counter catch rotatably mounted on the frame, means including a spring biasing the counter catch in one angular direction away from the counter to a first position wherein the counter catch is positioned radially outwardly of the counter ratchet teeth and engaging the counter stop surface to establish a starting position for the counter, a return spring urging the counter toward its said starting position, the counter catch being movable from said first position by the connecting means in the opposite angular direction upon trigger actuation to a second position wherein the counter catch is engageable with the counter ratchet teeth for releasably maintaining the counter in sequentially advanced indexed positions against the bias of its return spring, and the counter catch being movable by its biasing spring to said first position upon trigger release to permit counter reset by the counter return spring.

7. The firearm of claim 6 wherein the counter catch is movable by the connecting means upon trigger actuation to a third position intermediate said first and second positions, the angular displacement of the counter catch from said first position to said third position being sufficient to permit sear release of the hammer by the connecting means but insufficient to engage the counter ratchet, thereby allowing the counter return spring to reset the counter to its starting position when the hammer is returned from firing to cocked positions.

8. The firearm of claim 7 further including a combination safety and firing mode selector for selectively limiting angular displacement of the counter catch in said opposite angular direction from its said first position to establish its said second and third positions for burst and single shot modes of fire, the selector being engageable with the counter catch for blocking its movement from said first position to said third position to prevent sear release by the connecting means upon trigger actuation, thereby to establish a safety ON condition of the firearm.

9. A firearm comprising a frame, bolt means mounted on the frame for movement between a locked battery position and an unlocked recoil position, and a fire control mechanism operatively mounted on the frame and including a hammer movable from a firing position to a cocked position responsive to movement of the bolt means from its battery position to recoil position, the hammer being spring biased toward its firing position, a sear engageable with the hammer for releasably maintaining it in cocked position, and a selectively operable burst control means including a bolt operated automatic sear control operativelyv engaging the sear for hammer release upon movement of the bolt means to locked battery position, a counter movable responsive to hammer movement from cocked position to fir-v ing position for providing repeated hammer actuation of a preselected count, a cam movable in synchronism with the counter for selectively positioning the automatic sear control relative to the path of movement of the bolt means to its locked battery position to effect said preselected count, a manually actuatable trigger being mounted on the frame for operating the sear to release the hammer, the fire control mechanism including a housing, a pivot pin mounted on the housing and rotatably supporting the hammer, the counter being rotatably mounted on the hammer pivot pin, and a return spring biasing the counter in one angular direction toward a starting position, the counter being driven in an opposite angular direction from its starting position responsive to release of the hammer for rotation in said opposite angular direction from its said cocked position to said firing position, and the counter being returned in said one angular direction to itsstarting position by the return spring upon trigger release.

10. A firearm comprising a frame, bolt means mounted on the frame for movement between a locked battery position and an unlocked recoil position, abd a fire control mechanism operatively mounted on the frame and including a hammer movable from a firing position to a cocked position responsive to movement of the bolt means from its battery position to recoil position, the hammer being spring biased toward its firing position, a sear engageable with the hammer for releasably maintaining it in cocked position, and a selectively operable burst control means including a bolt operated automatic sear control operatively engaging the sear for hammer release upon movement of the bolt means to locked battery position, a counter movable responsive to hammer movement from cocked position to firing position for providing repeated hammer actuation of a preselected count, a cam movable in synchronism with the counter for selectively positioning the automatic sear control relative to the path of movement of the bolt means to its locked battery position to effect said preselected count, a manually actuatable trigger being mounted on the frame for operating the sear to release the hammer, the burst control means effecting repeated hammer actuation of a preselected maximum count established by the counter cam, automatic hammer actuation being interrupted by release of the trigger to effect a count less than said preselected maximum count, the counter being movable from a starting position and sequentially indexed in one direction in response to repeated hammer actuation to effect said preselected count, and a spring being connected to the counter for moving the counter in a direction opposite said one direction to reset the counter in said starting position upon release of the trigger.

11. A firearm comprising a frame, bolt means mounted on the frame for movement between a locked battery position and an unlocked recoil position, and a fire control mechanism operatively mounted on the frame and including a hammer movable from a firing position to a cocked position responsive to movement of the bolt means from its battery position to recoil position, the hammer being spring biased toward its firing position, a sear engageable with the hammer for releasably maintaining it in cocked position, and a selectively operable burst control means including a bolt operated automatic sear control operatively engaging the sear for hammer release upon movement of the bolt means to locked battery position, a counter movable responsive to hammer movement from cocked position to firing position for providing repeated hammer actuation of a preselected count, a cam movable in synchronism with the counter relative to the path of movement of the bolt means to its locked battery position to effect said preselected count, the counter being supported for rotation on the frame and having a ratchet formed thereon, a disengageable positive driving connection being provided between the hammer and the counter including a drive crank having a pawl normally positioned in noninterfering relation to the counter ratchet under hammer cocked conditions, the pawl being positively engaged with the counter ratchet upon hammer release to drive the counter in one angular direction away from a starting position, the pawl being disengaged from the counter ratchet responsive to hammer movement from firing to cocked positions, a counter return spring being provided for urging the counter in the opposite angular direction toward said starting position, and counter catch means for engaging the counter ratchet and releasably maintaining the counter in indexed positions angularly displaced from said starting position against. the bias of the counter return spring.

12. The firearm of claim 11 wherein the counter includes a stop surface in offset relation to the ratchet,

and wherein the counter catch is engageable with the counter stop surface for establishing said counter starting position.

13. The firearm of claim 12 further including a manually actuatable trigger mounted on the frame. connecting means connecting the trigger and the sear, the counter catch being movable by the connecting means toward the counter for engaging its ratchet upon trigger actuation and being movable away from the ratchet of the counter for engaging its stop surface upon trigger release.

14. The firearm of claim 1 1 wherein the hammer and counter are rotatably mounted on a common pivot pin supported on the frame, the disengageable positive driving connection including a spring biased hammer strut for urging the hammer toward firing position, the hammer strut having a bifurcated end and the drive crank having a pin rotatably supported on the hammer and engaging the bifurcated end of the hammer strut, the bifurcated end of the hammer strut and the drive crank pin having contact surfaces mutually engageable under hammer cocked conditions to effect withdrawal of the drive crank pawl from the counter ratchet under the biasing force of the hammer strut, the contact surface of thebifurcated end of the hammer strut being eccentrically positioned relative to the contact surface of the drive crank pin upon its being pivoted about said common pivot pin upon hammer release to urge the drive crank pawl into driving engagement with the counter ratchet.

15. A firearm comprising a frame, bolt means mounted on the frame for movement between a locked battery position and an unlocked recoil position, and a fire control mechanism operatively mounted on the frame and including a hammer movable from a firing position to a cocked position responsive to movement of the bolt means from its battery position to recoil position, the hammer being spring biased toward its firing position, a sear engageable with the hammer for releasably maintaining it in cocked position, and a selectively operable burst control means including a bolt operated automatic sear control operatively engaging the sear for hammer release upon movement of the bolt means to locked battery position, a counter movable responsive to hammer movement from cocked position to firing position for providing repeated hammer actuation of a preselected count, a cam movable in synchronism with the counter for selectively positioning the automatic sear control relative to the path of movement of the bolt means to its locked battery position to effect said preselected count, the counter including a ratchet and a stop surface in offset relation to the ratchet, a trigger actuated rotary sear lever mounted on the frame, a counter catch rotatably mounted on the frame and drivingly connected to the sear lever, a spring biasing the sear lever and the counter catch in one angular direction to establish a normal starting position for the counter by engagement of the counter stop surface with the counter catch, the counter catch being movable in the opposite angular direction toward the counter ratchet responsive to movement of the sear lever in said opposite angular direction for engaging the sear to release the'hammer upon trigger actuation, and the counter catch being movable away from the counter ratchet under the force of said spring responsive to movement of the sear lever in said one angular direction upon trigger release, and a counter return spring connected to the counter urging it toward said starting position for resetting the counter upon trigger release.

16. The firearm of claim 15 wherein a common pivot pin is mounted on the frame and supports the sear, sear lever and counter catch for rotation, and wherein a second common pivot pin is mounted on the frame in generally parallel relation to the first common pivot pin, the hammer and counter being rotatably supported on the second common pivot pin.

17. The firearm of claim 15 wherein the sear is movable relative to the sear lever upon engagement therewith to permit positive engagement with the hammer upon its return to cocked position.

18. The firearm of claim 15 further including a combination safety and firing mode selector including a control cam rotatably supported on the frame for engagement with the counter catch to control the angular displacement of the counter catch responsive to trigger actuation of the sear lever, a second spring between the sear lever and the counter catch biasing the counter catch toward the counter ratchet, the control cam having a safety position blocking counter catch movement and limiting sear lever movement in said opposite angular direction to a displacement insufficient to disengage the sear from the hammer, a single shot position permitting limited angular movement of the counter catch and limited sear lever displacement sufficient to disengage the sear from the hammer but insufficient to move the counter catch into engagement with the counter ratchet, and a burst position permitting angular movement of the counter catch and sear lever to effect disengagement of the sear from the hammer and successive engagement of the counter catch with the cam ratchet for releasably maintaining the counter in an advanced indexed position against the bias of its return spring.

19. A firearm comprising a frame, bolt means mounted on the frame for movement between a locked battery position and an unlocked recoil position, and a fire control mechanism operatively mounted on the frame and including a hammer movable from a firing position to a cocked position responsive to movement of the bolt means from its battery position to recoil position, the hammer being spring biased toward its firing position, a sear engageable with the hammer for releasably maintaining it in cocked position, and a selectively operable burst control means including a bolt operated automatic sear control operatively engaging the sear for hammer release upon movement of the bolt means to locked battery position, a counter movable responsive to hammer movement from cocked position to firing position for providing repeated hammer actuation of a preselected count, a cam movable in synchronism with the counter for selectively positioning the automatic sear control relative to the path of movement of the bolt means to its locked battery position to effect said preselected count, the sear control including a trip lever normally biased toward an inoperative position in noninterfering relation to the path of movement of the bolt means, the sear control being selectively operated by the cam, upon counter movement to provide said preselected count, to move the trip lever into an operative position in the path of movement of the bolt means to its locked battery position for operating the sear responsive to engagement of the trip lever by the bolt means, the sear control being disengaged by the cam to permit return of the trip lever to its inoperative position after said preselected count has been effected by the counter.

20. The firearm of claim 19 wherein the bolt means includes a bolt locking block movable between a first position in unlocked relation to the frame and a second position releasably locking the bolt to the frame, the bolt locking block engaging the trip lever of the sear control in its operative position upon movement of the bolt locking block from its first to second positions.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 I v Dated November 27 1973 Inventor(s) Henry A. Into It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

ColumnS, line 12 insert -controlafter "fire".

Column 11, line 46 cancel "disengageable position" and substitute therefor -disengageable positive".

and sealed this 16th day of April 197A.

Signed (SEAL) Atte st:

EDWARD M.FLETCHER,JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents VUSC OMM-DC wan-Poo ".5. GOVERNMENT PRINTING OFFICE U. O-QQI-SM.

FORM PC4050 (IO-69) UNITED STATES PATENT oFm CERTIFICATE OF 3:774 Dated November 27 1973 Patent No Inventor(s) Henry A. Into It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 12 insert -controlafter "fire".

Column 11, line 46 cancel "disengageable position" and substitute therefor --disengageable positive-.

Signed and sealed this 16th day of April 197A.

(SEAL) Atte st:

EDWARD I LFLETGHERJRQ C. MARSHALL DANN Attesting Officer Commissioner of Patents USCOMM'DC eosn-Pon F O RM PC3-1050 (10-69) w u.s eovenmnsn'r manna OFFICE: lug o-us-su 

1. A firearm comprising a frame, bolt means mounted on the frame for movement between a locked battery position and an unlocked recoil position, and a fire control mechanism operatively mounted on the frame and including a hammer movable from a firing position to a cocked position responsive to movement of the bolt means from its battery position to recoil position, the hammer being spring biased toward its firing position, a sear engageable with the hammer for releasably maintaining it in cocked position, and a selectively operable burst control means including a bolt operated automatic sear control operatively engaging the sear for hammer release upon movement of the bolt means to locked battery position, a counter movable responsive to hammer movement from cocked position to firing position for providing repeated hammer actuation of a preselected count, and a cam movable in synchronism with movement of the counter for selectively positioning the automatic sear control relative to the path of movement of the bolt means to effect said preselected count, the automatic sear control being disposed by the counter-operated cam in interfering relation to the path of bolt means movement into locked battery position to repeatedly operate the sear to effect hammer release of said preselected count in response to and in timed relation to movement of the bolt means from recoil position into locked battery position, the automatic sear control being positioned by the counteroperated cam in noninterfering relation to the path of bolt means movement upon the hammer being released a number of times corresponding to said preselected count for searing up the hammer.
 2. The firearm of claim 1 further including a manually actuatable trigger mounted on the frame, connecting means connecting the trigger and the sear, the hammer and the counter being rotatably supported on a common pivot pin mounted on the frame.
 3. The firearm of claim 1 further including a disengageable positive driving connection between the hammer and the counter drivingly engaging the counter during hammer movement from cocked position to firing position for indexing the counter during hammer actuation, the positive driving connection between the hammer and the counter being disengaged upon return movement of the hammer from firing position to cocked position.
 4. The firearm of claim 1 wherein a manually actuatable trigger is mounted on the frame for operating the sear to release the hammer, wherein the burst control means effects repeated hammer actuation of a preselected maximum count established by the counter cam, and wherein automatic hammer actuation may be interrupted by release of the trigger to effect a count less than said preselected maximum count.
 5. The firearm of claim 1 further including a fire mode selector for conditioning the counter to provide the counting function.
 6. A firearm comprising a frame, bolt means mounted on the frame for movement between a locked battery position and an unlocked recoil position, and a fire control mechanism operatively mounted on the frame and including a hammer movable from a firing position to a cocked position responsive to movement of the bolt means from its battery position to recoil position, the hammer being spring biased toward its firing position, a sear engageable with the hammer for releasably maintaining it in cocked position, and a selectively operable burst control means including a bolt operated automatic sear control operatively engaging the sear for hammer release upon movement of the bolt means to locked battery position, a counter movable responsive to hammer movement from cocked position to firing position for providing repeated hammer actuation of a preselected count, a cam movable in synchronism with the counter for selectively positioning the automatic sear control relative to the path of movement of the bolt means to its locked battery position to effect said preselected count, a disengageable position driving connection between the hammer and the counter drivingly engaging the counter during hammer movement from cocked position to firing position for indexing the counter during hammer actuation, the positive driving connection between the hammer and the counter being disengaged upon return movement of the hammer from firing position to cocked position, the counter having ratchet teeth and a stop surface in offset relation to the ratchet teeth, a counter catch rotatably mounted on the frame, means including a spring biasing the counter catch in one angular direction away from the counter to a first position wherein the counter catch is positioned radially outwardly of the counter ratchet teeth and engaging the counter stop surface to establish a starting position for the counter, a return spring urging the counter toward its said starting position, the counter catch being movable from said first position by the connecting means in the opposite angular direction upon trigger actuation to a second position wherein the counter catch is engageable with the counter ratchet teeth for releasably maintaining the counter in sequentially advanced indexed positions against the bias of its return spring, and the counter catch being movable by its biasing spring to said first position upon trigger release to permit counter reset by the counter return spring.
 7. The firearm of claim 6 wherein the counter catch is movable by the connecting means upon trigger actuation to a third position intermediate said first and second positions, the angular displacement of the counter catch from said first position to said third positIon being sufficient to permit sear release of the hammer by the connecting means but insufficient to engage the counter ratchet, thereby allowing the counter return spring to reset the counter to its starting position when the hammer is returned from firing to cocked positions.
 8. The firearm of claim 7 further including a combination safety and firing mode selector for selectively limiting angular displacement of the counter catch in said opposite angular direction from its said first position to establish its said second and third positions for burst and single shot modes of fire, the selector being engageable with the counter catch for blocking its movement from said first position to said third position to prevent sear release by the connecting means upon trigger actuation, thereby to establish a safety ''''ON'''' condition of the firearm.
 9. A firearm comprising a frame, bolt means mounted on the frame for movement between a locked battery position and an unlocked recoil position, and a fire control mechanism operatively mounted on the frame and including a hammer movable from a firing position to a cocked position responsive to movement of the bolt means from its battery position to recoil position, the hammer being spring biased toward its firing position, a sear engageable with the hammer for releasably maintaining it in cocked position, and a selectively operable burst control means including a bolt operated automatic sear control operatively engaging the sear for hammer release upon movement of the bolt means to locked battery position, a counter movable responsive to hammer movement from cocked position to firing position for providing repeated hammer actuation of a preselected count, a cam movable in synchronism with the counter for selectively positioning the automatic sear control relative to the path of movement of the bolt means to its locked battery position to effect said preselected count, a manually actuatable trigger being mounted on the frame for operating the sear to release the hammer, the fire control mechanism including a housing, a pivot pin mounted on the housing and rotatably supporting the hammer, the counter being rotatably mounted on the hammer pivot pin, and a return spring biasing the counter in one angular direction toward a starting position, the counter being driven in an opposite angular direction from its starting position responsive to release of the hammer for rotation in said opposite angular direction from its said cocked position to said firing position, and the counter being returned in said one angular direction to its starting position by the return spring upon trigger release.
 10. A firearm comprising a frame, bolt means mounted on the frame for movement between a locked battery position and an unlocked recoil position, abd a fire control mechanism operatively mounted on the frame and including a hammer movable from a firing position to a cocked position responsive to movement of the bolt means from its battery position to recoil position, the hammer being spring biased toward its firing position, a sear engageable with the hammer for releasably maintaining it in cocked position, and a selectively operable burst control means including a bolt operated automatic sear control operatively engaging the sear for hammer release upon movement of the bolt means to locked battery position, a counter movable responsive to hammer movement from cocked position to firing position for providing repeated hammer actuation of a preselected count, a cam movable in synchronism with the counter for selectively positioning the automatic sear control relative to the path of movement of the bolt means to its locked battery position to effect said preselected count, a manually actuatable trigger being mounted on the frame for operating the sear to release the hammer, the burst control means effecting repeated hammer actuation of a preselected maximum count established by the counter cam, automatic hammer actuation being interrupted by reLease of the trigger to effect a count less than said preselected maximum count, the counter being movable from a starting position and sequentially indexed in one direction in response to repeated hammer actuation to effect said preselected count, and a spring being connected to the counter for moving the counter in a direction opposite said one direction to reset the counter in said starting position upon release of the trigger.
 11. A firearm comprising a frame, bolt means mounted on the frame for movement between a locked battery position and an unlocked recoil position, and a fire control mechanism operatively mounted on the frame and including a hammer movable from a firing position to a cocked position responsive to movement of the bolt means from its battery position to recoil position, the hammer being spring biased toward its firing position, a sear engageable with the hammer for releasably maintaining it in cocked position, and a selectively operable burst control means including a bolt operated automatic sear control operatively engaging the sear for hammer release upon movement of the bolt means to locked battery position, a counter movable responsive to hammer movement from cocked position to firing position for providing repeated hammer actuation of a preselected count, a cam movable in synchronism with the counter relative to the path of movement of the bolt means to its locked battery position to effect said preselected count, the counter being supported for rotation on the frame and having a ratchet formed thereon, a disengageable positive driving connection being provided between the hammer and the counter including a drive crank having a pawl normally positioned in noninterfering relation to the counter ratchet under hammer cocked conditions, the pawl being positively engaged with the counter ratchet upon hammer release to drive the counter in one angular direction away from a starting position, the pawl being disengaged from the counter ratchet responsive to hammer movement from firing to cocked positions, a counter return spring being provided for urging the counter in the opposite angular direction toward said starting position, and counter catch means for engaging the counter ratchet and releasably maintaining the counter in indexed positions angularly displaced from said starting position against the bias of the counter return spring.
 12. The firearm of claim 11 wherein the counter includes a stop surface in offset relation to the ratchet, and wherein the counter catch is engageable with the counter stop surface for establishing said counter starting position.
 13. The firearm of claim 12 further including a manually actuatable trigger mounted on the frame, connecting means connecting the trigger and the sear, the counter catch being movable by the connecting means toward the counter for engaging its ratchet upon trigger actuation and being movable away from the ratchet of the counter for engaging its stop surface upon trigger release.
 14. The firearm of claim 11 wherein the hammer and counter are rotatably mounted on a common pivot pin supported on the frame, the disengageable positive driving connection including a spring biased hammer strut for urging the hammer toward firing position, the hammer strut having a bifurcated end and the drive crank having a pin rotatably supported on the hammer and engaging the bifurcated end of the hammer strut, the bifurcated end of the hammer strut and the drive crank pin having contact surfaces mutually engageable under hammer cocked conditions to effect withdrawal of the drive crank pawl from the counter ratchet under the biasing force of the hammer strut, the contact surface of the bifurcated end of the hammer strut being eccentrically positioned relative to the contact surface of the drive crank pin upon its being pivoted about said common pivot pin upon hammer release to urge the drive crank pawl into driving engagement with the counter ratchet.
 15. A firearm comprising a frame, bolt means mounted on the frame for movement between a locked battery position and an unlocked recoil position, and a fire control mechanism operatively mounted on the frame and including a hammer movable from a firing position to a cocked position responsive to movement of the bolt means from its battery position to recoil position, the hammer being spring biased toward its firing position, a sear engageable with the hammer for releasably maintaining it in cocked position, and a selectively operable burst control means including a bolt operated automatic sear control operatively engaging the sear for hammer release upon movement of the bolt means to locked battery position, a counter movable responsive to hammer movement from cocked position to firing position for providing repeated hammer actuation of a preselected count, a cam movable in synchronism with the counter for selectively positioning the automatic sear control relative to the path of movement of the bolt means to its locked battery position to effect said preselected count, the counter including a ratchet and a stop surface in offset relation to the ratchet, a trigger actuated rotary sear lever mounted on the frame, a counter catch rotatably mounted on the frame and drivingly connected to the sear lever, a spring biasing the sear lever and the counter catch in one angular direction to establish a normal starting position for the counter by engagement of the counter stop surface with the counter catch, the counter catch being movable in the opposite angular direction toward the counter ratchet responsive to movement of the sear lever in said opposite angular direction for engaging the sear to release the hammer upon trigger actuation, and the counter catch being movable away from the counter ratchet under the force of said spring responsive to movement of the sear lever in said one angular direction upon trigger release, and a counter return spring connected to the counter urging it toward said starting position for resetting the counter upon trigger release.
 16. The firearm of claim 15 wherein a common pivot pin is mounted on the frame and supports the sear, sear lever and counter catch for rotation, and wherein a second common pivot pin is mounted on the frame in generally parallel relation to the first common pivot pin, the hammer and counter being rotatably supported on the second common pivot pin.
 17. The firearm of claim 15 wherein the sear is movable relative to the sear lever upon engagement therewith to permit positive engagement with the hammer upon its return to cocked position.
 18. The firearm of claim 15 further including a combination safety and firing mode selector including a control cam rotatably supported on the frame for engagement with the counter catch to control the angular displacement of the counter catch responsive to trigger actuation of the sear lever, a second spring between the sear lever and the counter catch biasing the counter catch toward the counter ratchet, the control cam having a safety position blocking counter catch movement and limiting sear lever movement in said opposite angular direction to a displacement insufficient to disengage the sear from the hammer, a single shot position permitting limited angular movement of the counter catch and limited sear lever displacement sufficient to disengage the sear from the hammer but insufficient to move the counter catch into engagement with the counter ratchet, and a burst position permitting angular movement of the counter catch and sear lever to effect disengagement of the sear from the hammer and successive engagement of the counter catch with the cam ratchet for releasably maintaining the counter in an advanced indexed position against the bias of its return spring.
 19. A firearm comprising a frame, bolt means mounted on the frame for movement between a locked battery position and an unlocked recoil position, and a fire control mechanism operatively mounted on the frame and including a hammer movable from a firing posItion to a cocked position responsive to movement of the bolt means from its battery position to recoil position, the hammer being spring biased toward its firing position, a sear engageable with the hammer for releasably maintaining it in cocked position, and a selectively operable burst control means including a bolt operated automatic sear control operatively engaging the sear for hammer release upon movement of the bolt means to locked battery position, a counter movable responsive to hammer movement from cocked position to firing position for providing repeated hammer actuation of a preselected count, a cam movable in synchronism with the counter for selectively positioning the automatic sear control relative to the path of movement of the bolt means to its locked battery position to effect said preselected count, the sear control including a trip lever normally biased toward an inoperative position in noninterfering relation to the path of movement of the bolt means, the sear control being selectively operated by the cam, upon counter movement to provide said preselected count, to move the trip lever into an operative position in the path of movement of the bolt means to its locked battery position for operating the sear responsive to engagement of the trip lever by the bolt means, the sear control being disengaged by the cam to permit return of the trip lever to its inoperative position after said preselected count has been effected by the counter.
 20. The firearm of claim 19 wherein the bolt means includes a bolt locking block movable between a first position in unlocked relation to the frame and a second position releasably locking the bolt to the frame, the bolt locking block engaging the trip lever of the sear control in its operative position upon movement of the bolt locking block from its first to second positions. 